When does Charge Mode make sense?

I don't have a plug-in yet (hopefully tomorrow). My research shows there are very few free charge stations available. Those that demand payment are so expensive it's cheaper to drive on gas. I don't plan on using any charge stations away from our own garage. If you have an EV car you may not have a choice. With a PHEV you can use which ever is less expensive.

 

So since my only local refuge for free charging no longer permits freeloaders, and I can't charge at my apartment, I am without a plug-in location for a while. Given the colder temps, here is what I was thinking to make the most out of Charge Mode for my work commute (about 8 miles). Use electric in the morning, since it would take a lot of energy to warm up the engine anyway. But on the return trip, recharge using Charge Mode, and use it the whole way. This way, the engine/coolant stay hot, and thus make the most efficient use of engine and heat. If I need to cram in multiple short trips, e.g., shopping, only use engine if the coolant will stay hot.

 

Take advantage of the coolant adjust heated up. You can drive a surprising distance with just electricity with that warmth supplied via the engine having run earlier.

With an aftermarket gauge, you can watch coolant temperature to see that taking place.

 

Here's a recent test I did before reading this post here.

 

Yes I know, I have a ScanGauge II.

So, a round-trip test today to work and back, started and finished at 48% charge, on electric to work and on charge mode most of the way back (some coasting on electric), and I'm on winter tires. I ended up a net 55.0 mpg. *shrug*

 

Do you have any mpg or mpge numbers available from the trip that might shed light charge mode efficiency.
I understand what you're saying concerning the lack of an efficiency hit, I'm more interested in understanding how many EV estimated miles were gained pre miles driven in charge mode, if you noticed on that trip.
I'd run the numbers myself if I was close enough to a hwy that allowed it.

 

Here's some real-world data for you to ponder:

Hybrids achieve high efficiency by seeking out opportunity. That gain can be boosted even further the choice of how & when is carefully considered & control. Charge-Mode provides that benefit... if used wisely.

Gas engines waste quite a bit of energy. A source of that waste comes from not carrying much load. The combustion process is most efficient when the engine is being utilized more, closer to its full potential. Charge-mode allows you to take advantage of that.

In this example, I activate Charge-Mode on 3 different occasions. This running of the engine more than needed results in electricity being generated to recharge the battery... which I take advantage of afterward. Watch before & after I get on the highway. Also watch as I cruise along the back country road as I get close to the end of my commute home.

Since this demonstration took place in the winter, I also took advantage of the other wasted energy from the gas engine: heat. When I shut off Charge-Mode, the system switches back to EV mode. So, rather than using electricity to provide heat while driving with the engine off, the cabin warming is provided by heated engine coolant.

Used wisely, there can be an overall MPG benefit. When on long trips, like vacation when there is no charging available at the destination, I will take advantage of Charge-Mode to supply electricity for later when going out in the evening for dinner or getting coffee the next morning, using EV to avoid engine warm-up.

Notice the results in this case. That's quite impressive. 49 MPG overall, despite the cold. There is 1 mile of electricity still available for EV at the end too.

 

Thanks John, I really appreciate all the time you take making and sharing these videos as well as your other prius info ...
I now have a phone that'll run torque but the first time I tried to pair - torque paired up to my elm327 but it looked like my wifi was interfering or something. I'll try again today with both elms and see what else I can find out about using torque (free first to get used to it and see how or if it works with prime) before I get lost in pro. I've already shot one video - with no traffic around early in the morning - not for public release and I haven't even had time to look at it myself anyways. I hope I'll be able to add at least some useful stuff here in the future.

 

When you have depleted the ev portion of your battery, and while in HV mode, you get a few long glides in and deplete your hv portion of the battery, doesn't the car automatically go into charge mode for a while ?

Until the HV portion is restored or you stop, or if you feather that accelerator to turn off the ICE.

Just my opinion, but this automatic HV charge mode doesn't seam any worse that the manual mode of turning it on.

 

Technically yes, after the prime EV portion of the pack is depleted and the ICE comes on I have seen it charge and return to EV mode.
Unless I completely missed something that charge mode is the same as a non-plugin prius charge..
edit: and a different charge algorithm form the charge mode one gets from manually switching on charge mode.

 

To compliment @john1701a: Prius Prime Plus in my hands | Page 25 | PriusChat

Uh, not that I've observed. You have to enable CHARGE mode.

WARNING: do not run out of gas and battery at the same time. It sets a flag and to start the car, you'll have to do a 12V power-on reset (i.e., disconnect and reconnect the 12V ground.)

Bob Wilson

 

It's a great question. Here's the situation I am experimenting with. One of my regular drives is longer than my EV range. It is mountainous with steep hills in places and longer more level and downhill stretches in other. There is also some city driving at the far end. I try and use EV for the steep parts and in the city and use charge mode to extend my range back home again. I'm using charge mode on the more level terrain where the ICE does not have to work hard. I use EV up the steep parts which avoids using the ICE when it would be working hard. Don't know for sure if this has a net benefit. So I ask... does charge mode on level terrain use more fuel than using HV on steep climbs? I'd think this was a good trade off.

 

no way to know without repetitive tests to get an average, depends on so many factors.

 

I’m not going to review all 53 comments, so sorry if this was already mentioned

I *think* the main reason the Prime has Charge Mode is due to some cities (mostly in Europe?) may restrict gas burners in the central business districts. This way folks can ensure they have enough battery range to get to their destination. Of course I could be wrong

 

I have been expirameting with Charge mode slightly differently.. I usually drive 65 -75 mph. When going down hill try and harvest the trons from inertia. When known acceleration is needed. Like entering the hiway. Or climbing hills. I put it into CM. if the engine is running. I want max charge. It's fun to accelerate, downhill in neutral too.

Via Prius Chat for Android

 

We use Charging mode for all long distance driving. As soon as the drive battery is empty, we begin recharging it.

We usually set cruise control at 81mph. Uphill, downhill makes no difference.

 

I'm having trouble wrapping my mind around the concept that "Charge" mode does not require more work from the ICE.

I recall (incorrectly?) that when the ICE was already running, invoking charge mode created additional effort. If not, then why is it not always automatically invoked when the ICE is running and the battery is less than "full"?

 

Same miles-to-the-gallon fuel economy.

Oversight by the programmers.

 

That cannot be possible. If it were so you’d have a perpetual motion machine. To create energy you would have to expend energy and since ICE engines are only about 30% efficient you are burning additional fuel to do it.

 

It does require more work, and thus more fuel. Now, the extra fuel burned could be compensated for by the higher efficiency in EV mode.

If your use of charge mode results in the same fuel economy as just using hybrid mode, you are subjecting the battery to DC fast charges for no gain.